In recent years, classroom digitization has been advancing. For example, techniques have been proposed that records information of recording the voice of an instructor and capturing content to be displayed on classroom monitors as recorded information, and, at the timing when a page number of the content changes, synchronization information for the content and recorded information is created and recorded (for example, refer to Patent Literature 1). In the technique of Patent Literature 1, via a network, content and recorded information can be reproduced in synchronization with each other at a timing when the page number of the content changes.